Although wireless communication technologies have been developed up to LTE based on Wideband Code Division Multiple Access (WCDMA), demands and expectation of users and service providers are still on the rise. Since the development of other wireless access technologies is in progress, new technology evolution is needed to achieve future competitiveness. Such new technologies require a reduction in cost per bit, an increase in service availability, flexible use of frequency bands, simple structured and open interfaces, and appropriate power consumption of UEs.
Recently, standardization of the successor to LTE is in progress in 3 GPP. In this specification, the successor will be referred to as “LTE-Advanced” or “LTE-A”. Differences of the LTE-A system from the LTE system include system bandwidth and introduction of a repeater. The LTE-A system aims to support a wideband of up to 100 MHz. The LTE-A system uses carrier aggregation or bandwidth aggregation technology to achieve a wideband using a plurality of frequency blocks. In the carrier aggregation technology, a plurality of frequency blocks is used as one large logic frequency band in order to use a wider frequency band. The bandwidth of each frequency block may be defined based on the bandwidth of a system block used in the LTE system. Each frequency block is transmitted using a component carrier.
In order to guarantee accurate uplink channel estimation, the 3 GPP-LTE-A system supports aperiodic SRS transmission in addition to conventional periodic SRS transmission. Aperiodic SRS configuration information and uplink transmission power control for aperiodic SRS transmission are needed to support such aperiodic SRS transmission. However, detailed aperiodic SRS configuration information and methods for controlling uplink transmission power for aperiodic SRS transmission have not yet been suggested.